High-Performance Organic Laser Semiconductor Enabling Efficient Light-Emitting Transistors and Low-Threshold Microcavity Lasers.

Yin, Fan; De, Jianbo; Liu, Meihui; Huang, Han; Geng, Hua; Yao, Jiannian; Liao, Qing; Fu, Hongbing · Nano Lett · 2022

basic_science · Level V

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Abstract

An organic light-emitting transistor (OLET) is a candidate device architecture for developing electrically pumped organic solid-state lasers, but it remains a critical challenge because of the lack of organic semiconductors that simultaneously possess a high solid-state emission efficiency (Φ<sub>s</sub>), a high and balanced ambipolar mobility (μ<sub>h,e</sub>), and a large stimulated emission cross-section. Here, we designed a molecule of 4,4'-bis(2-dibenzothiophenyl-vinyl)-biphenyl (DBTVB) and prepared its ultrathin single-crystal microplates with herringbone packing arrangements, which achieve balanced mobilities of μ<sub>h</sub> = 3.55 ± 0.5 and μ<sub>e</sub> = 2.37 ± 0.5 cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup>, a high Φ<sub>s</sub> of 85 ± 3%, and striking low-threshold laser characteristics. Theoretical and experimental investigations reveal that a strong electronic coupling and a small reorganization energy ensure efficient charge transport; meanwhile, the exciton-vibration effect and negligible π-π orbital overlap give rise to highly emissive H-aggregates and facilitate laser emission. Furthermore, OLET-based DBTVB crystals offer an internal quantum efficiency approaching 100% and a record-high electroluminescence external quantum efficiency of 4.03%.